After a long wait, NASA's asteroid probe OSIRIS-REx is finally returning to Earth with a sample of the asteroid BENNU, which provides basic information about the asteroid BENNU, the mission objectives, significance, and the recently started two-year return journey.
After nearly two and a half years together, NASA's Pluto probe has bid farewell to the asteroid Bennu and begun its return journey.
The Pluto probe is expected to arrive on Earth in September 2023 and will bring back some dust from the "Bennu" asteroid. These dust samples help uncover the secrets of the formation of the solar system and the origin of life on Earth.
The Pluto probe completed its last flyby before flying out of orbit on the Bennu asteroid. In the last close encounter, the probe spent 5.9 hours photographing the Bennu asteroid in all directions, a little longer than its full rotation period. The shooting was only 2.1 miles (3.5 kilometers) from the planet's surface, the closest to Bennu since the sample collection mission began.
Amy. Simon is a planetary scientist at NASA's Goddard Space Flight Center. She explained to Inverse magazine that the main purpose of the flyby was to observe the sample collection site for the last time.
"When we take the samples and leave, there is a lot of debris and dust that prevents us from being able to see the planet's surface clearly," Simon told Inverse Magazine. "The last flyby was mainly to be able to see if there had been any changes to the sample collection point, such as whether we had left a crater or whether there were new components that had not been detected before."
During its last flyby mission, Pluto collected 4GB of data. However, scientists will have to wait until April 13 to receive data sent back to Earth by Pluto, and until then, they will have to wait.
The Pluto probe maintains communication with ground-based control centers on Earth through a deep-space network that is also the communication system used by NASA to implement a series of space missions, including the Perseverance Mars rover. The Pluto probe takes 4 to 6 hours a day to download data and sends it back at a rate of 412 kilobits per second (about 186 megabytes per hour), so scientists will have to wait several days to receive the latest data transmitted back by the Pluto probe.
1. Background of the mission
Since December 2018, the Pluto probe has orbited the planet Bennu. Its mission is mainly to take samples of this ancient planet and bring them back to Earth for analysis. On October 20, 2020, the probe successfully landed on the surface of the planet and, through a continuous take-off sample collection mechanism, grabbed rock samples with the help of a robotic arm – a process that is a bit like a vacuum cleaner sucking up loose material from the planet Bennu.
2. What have we learned about the planet Bennu?
Before the Pluto probe returned with samples, it had already provided scientists with a wealth of new insights into the planet Bennu and other planets in close contact with Earth.
Simon said: "In fact, we have gained a lot from this mission. In addition to the well-known sample collection tasks, we also accomplished two main goals. ”
One of the mission's goals was to calculate how much the planet's orbit would change when it interacted with the Sun, and to analyze the planet's composition.
Simon admitted that by the time the Pluto probe arrived on the planet Bennu, the planet had already moved 185 kilometers from where the mission team had previously predicted.
"Its trajectory is constantly changing, which is very interesting. This information is also very important for us to understand how such a near-Earth planet would affect Earth. Simon said.
Based on the probe's observations, the team judged that the planet's rotation rate was gradually accelerating at a pace of 1 second per hundred years. While, this may sound trivial, it suggests that the planet Bennu is just a "rubber pile" made of dust and rock that gathers under gravity, rather than a solid.
Pluto's capture of the planet also proved for the first time that there is no atmosphere on the surface of the planet but thermal rupture. By measuring thermal ruptures, scientists can determine the age of the planets.
Heat rupture also occurs on Earth. On our planet, rocks are exposed to sunlight during the day and break apart at night. As rocks expand and contract, the increased pressure causes them to crack and eventually split into smaller pieces.
The rocks on the planet Bennu are like rocks on Earth, and have experienced different temperatures day and night. Temperatures can reach as high as 127 degrees Celsius (260 degrees Fahrenheit) during the day and plummet to minus 73 degrees Celsius (minus 99 degrees Fahrenheit) at night.
Previously, scientists believed that a planet like Bennu could have thermal rupture, but they didn't have any evidence until Pluto first demonstrated the idea.
3. When will the Pluto probe leave the planet Bennu?
The Pluto probe will depart the orbit of the planet Bennu on May 10 and embark on a two-year return journey. Because one of The Bennu's orbits overlaps earth's own orbital path, the return journey will consume less fuel boost than the return journey from other asteroids.
Michelle. Murio is the director of the Pluto program at NASA's Goddard Space Flight Center in Maryland. "Leaving the Bennu asteroid's vicinity in May is our best time, and this departure will consume the least amount of onboard fuel for the probe," he wrote in a note. ”
The probe will continue to orbit the Bennu asteroid in a relaxed orbit until it leaves as planned.
Mission target of the Pluto probe
On September 8, 2016, the Pluto probe was successfully launched with six equipment for mapping the Bennu asteroid, recording sample collection points, and other observations.
The mission is significant, as it is NASA's first attempt to land an asteroid and bring back samples of these rare objects. There have been two similar missions before: Genesis and Stardust have visited comets and brought back some samples. However, Genesis failed to land, resulting in damage to the effective load of the aircraft.
5. Why did the Pluto probe bring back asteroid samples?
Much of what we know about planets comes from meteorites, fragments left behind when the meteorite matrix passes through Earth. These meteorites may undergo some important changes as they pass through the Earth's atmosphere.
Unchanged asteroid samples are essential to explore our origins. Scientists believe that asteroids are made up of ancient material that formed the solar system billions of years ago, and asteroid research provides clues to our understanding of the origins of planets, including Earth.
With an orbital period of 436.6 days, Bennu is a rare Class B asteroid – one of the most primitive asteroids. Since its formation 4 billion years ago, Bennu has hardly changed. It possesses large amounts of carbon, organic molecules, and amino acids that form the basis of life.
After studying these asteroid samples in the laboratory, scientists will have a better understanding of the composition of asteroids and the material that forms these space objects.
When scientists look at asteroids or other space objects through the lens of a probe, they are limited by the equipment carried by the probe and cannot decompose the real ore on the surface of the planet, and studying samples in the laboratory becomes a completely different situation.
"Yeah, it's very interesting," Simon said, "and we can get more information on the asteroid samples, like, how brittle are they?" How hard is it? As well as different compositions, etc. ”
"I think we get a lot of interesting material and information from it." She added.
The mission isn't just about trying to trace our origins, it's also an effective way to protect the planet.
Bennu approaches Earth every six years, with a minimum distance of 0.002 astronomical units. For nearly 150 years, the chances of it hitting Earth were slim. By studying Bennu's orbit and the thrusts that affect its path, scientists were able to create a more efficient model of the orbit of an asteroid, resulting in a more accurate chance of hitting Earth.
6. When will the Pluto probe return to Earth?
The Pluto probe is scheduled to return to Earth on September 24, 2023, while bringing back loads that far exceed expectations.
Project members predicted that the total amount of material Pluto would receive from the surface of Bennu may far exceed the 2-ounce requirement set at the beginning of the mission.
"We don't have absolute estimates, but we know there should be a lot." Simon said.
In 2020, after the probe took samples, NASA noticed that the probe's robotic arm was leaking some material — its container couldn't be closed because it took too many unnecessary samples. Thankfully, the probe was able to load the samples.
Pluto's sample capsule will pass through Earth's atmosphere and land in the Utah test training area with the help of a parachute.
When the team members receive the sample module, they send it to the storage facility at NASA's Jonson Space Center in Houston.
After that, the agency will distribute samples to laboratories around the world, enabling international teams of scientists to conduct simultaneous research to explore the formation of the solar system as well as the Earth.
BY: inverse
FY: Autumn
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